As known, in motor vehicles the differential assembly transmits motion from a propeller shaft to a pair of reciprocally counterposed, coaxial drive axles which rotably feed the drive wheels.
Specifically, the differential assembly is arranged in an oil bath inside a fixed casing and comprises a supporting box, usually of cast iron, having two reciprocally opposite openings crossed by the ends of the two drive axles and carrying an outer ring gear in a relative fixed position.
The ring gear has a toothing meshing with the pinion integral with the propeller shaft, thus defining a speed reduction ratio, for rotably feeding the supporting box about the axis defined by the two drive axles.
The supporting box accommodates a planetary gear set comprising a pair of satellite gears, a pair of planetary gears meshing with the satellite gears and a satellite gear carrier pin, whose ends are coupled to respective anchoring portions of the supporting box.
The satellite gear carrier pin extends in the direction orthogonal to the drive axles, turns along with the supporting box, while each of the planetary gears is mounted, in a fixed angular position, onto the end of a respective drive axle to rotationally feed it.
The position of the satellite gears and/or the planetary gears is normally adjusted during assembly by appropriately mounted spacer members, whose thickness may be selected to compensate for possible clearance due to machining or coupling tolerance with respect to the supporting box and/or the other gears.
The differentials of the known type described above are poorly satisfactory, because they have a relatively high number of components and require relatively long times for choosing and mounting the aforesaid spacer members.
Furthermore, the solutions described above are not capable of adjusting the position of the gears automatically to compensate for possible clearance due to wear occurring during operation, and of constantly maintaining the satellite gears and the planetary gears correctly reciprocally meshed.